diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # cpkg
 
+## 0.2.3.0
+
+  * Add `garbage-collect` subcommand
+  * Add `uninstall` subcommand
+  * Add `nuke-cache` subcommand
+
 ## 0.2.2.0
 
   * Add `printLdLibFlags` function and add functionality to CLI interface
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -255,14 +255,14 @@
 -------------------------------------------------------------------------------
  Language             Files       Lines         Code     Comments       Blanks
 -------------------------------------------------------------------------------
- Bash                     5          52           44            3            5
- Cabal                    1         154          140            0           14
+ Bash                     3          50           40            5            5
+ Cabal                    1         157          143            0           14
  Cabal Project            1           4            3            0            1
- Dhall                    3        4660         4190            3          467
- Haskell                 31        1741         1428           29          284
- Markdown                 6         534          450            0           84
- YAML                     4         157          142            0           15
+ Dhall                    3        5191         4681            8          502
+ Haskell                 32        1949         1602           37          310
+ Markdown                 3         516          426            0           90
+ YAML                     4         148          133            0           15
 -------------------------------------------------------------------------------
- Total                   51        7302         6397           35          870
+ Total                   47        8015         7028           50          937
 -------------------------------------------------------------------------------
 ```
diff --git a/app/Main.hs b/app/Main.hs
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -14,18 +14,21 @@
 
 data DumpTarget = Linker { _pkgGet :: String }
                 | Compiler { _pkgGet :: String }
-                | PkgConfig { _pkgGet :: String }
+                | PkgConfig { _pkgGets :: [String] }
                 | IncludePath { _pkgGet :: String }
                 | LibPath { _pkgGet :: String }
                 | LdLibPath { _pkgGets :: [String] }
 
 data Command = Install { _pkgName :: String, _verbosity :: Verbosity, _target :: Maybe Platform, _static :: Bool, _global :: Bool, _packageSet :: Maybe String }
+             | Uninstall { _pkgStr :: String, _verbosity :: Verbosity, _target :: Maybe Platform }
              | Check { _dhallFile :: String, _verbosity :: Verbosity }
              | CheckSet { _dhallFile :: String, _verbosity :: Verbosity }
              | Dump { _dumpTarget :: DumpTarget, _host :: Maybe Platform }
              | DumpCabal { _pkgGetsCabal :: [String], _host :: Maybe Platform }
              | List { _packageSet :: Maybe String }
              | Nuke
+             | NukeCache
+             | GarbageCollect { _verbosity :: Verbosity }
 
 verbosityInt :: Parser Int
 verbosityInt = length <$>
@@ -54,7 +57,7 @@
 dumpTarget = hsubparser
     (command "linker" (info (Linker <$> package) (progDesc "Dump linker flags for a package"))
     <> command "compiler" (info (Compiler <$> package) (progDesc "Dump compiler flags for a package"))
-    <> command "pkg-config" (info (PkgConfig <$> package) (progDesc "Dump pkg-config path for a package")) -- TODO: make pkg-config recursive or something?
+    <> command "pkg-config" (info (PkgConfig <$> some package) (progDesc "Dump pkg-config path for a package")) -- TODO: make pkg-config recursive or something?
     <> command "include" (info (IncludePath <$> package) (progDesc "Dump C_INCLUDE_PATH for a package"))
     <> command "library" (info (LibPath <$> package) (progDesc "Dump LD_LIBRARY_PATH or LIBRARY_PATH info for a package"))
     <> command "ld-path" (info (LdLibPath <$> some package) (progDesc "Dump LD_LIBRARY_PATH or LIBRARY_PATH for a package"))
@@ -63,12 +66,15 @@
 userCmd :: Parser Command
 userCmd = hsubparser
     (command "install" (info install (progDesc "Install a package from the global package set"))
+    <> command "uninstall" (info uninstall (progDesc "Uninstall a package"))
     <> command "check" (info check (progDesc "Check a Dhall expression to ensure it can be used to build a package"))
     <> command "check-set" (info checkSet (progDesc "Check a package set defined in Dhall"))
     <> command "dump" (info dump (progDesc "Display flags to link against a particular library"))
     <> command "dump-cabal" (info dumpCabal (progDesc "Display flags to use with cabal new-build"))
     <> command "list" (info list (progDesc "List all available packages"))
     <> command "nuke" (info (pure Nuke) (progDesc "Remove all globally installed libraries"))
+    <> command "nuke-cache" (info (pure NukeCache) (progDesc "Remove cached soure tarballs"))
+    <> command "garbage-collect" (info garbageCollect' (progDesc "Garbage collect redundant packages"))
     )
 
 list :: Parser Command
@@ -80,6 +86,15 @@
 dhallCompletions :: Mod ArgumentFields a
 dhallCompletions = ftypeCompletions "dhall"
 
+uninstall :: Parser Command
+uninstall = Uninstall
+    <$> argument str
+        (metavar "PACKAGE"
+        <> help "Name of package to uninstall"
+        <> completer (listIOCompleter allPackages))
+    <*> verbosity
+    <*> target
+
 install :: Parser Command
 install = Install
     <$> argument str
@@ -108,6 +123,9 @@
     (long "static"
     <> help "Build static libaries")
 
+garbageCollect' :: Parser Command
+garbageCollect' = GarbageCollect <$> verbosity
+
 check :: Parser Command
 check = Check <$> dhallFile <*> verbosity
 
@@ -149,6 +167,9 @@
     )
 
 run :: Command -> IO ()
+run (Uninstall pkId v host') = do
+    parsedHost <- parseHostIO host'
+    runPkgM v $ uninstallPkgByName pkId parsedHost
 run (Install pkId v host' sta glob pkSet) = do
     parsedHost <- parseHostIO host'
     runPkgM v $ buildByName (T.pack pkId) parsedHost pkSet sta glob
@@ -156,7 +177,7 @@
 run (CheckSet file' v) = void $ getPkgs v file'
 run (Dump (Linker name) host) = runPkgM Normal $ printLinkerFlags name host
 run (Dump (Compiler name) host) = runPkgM Normal $ printCompilerFlags name host
-run (Dump (PkgConfig name) host) = runPkgM Normal $ printPkgConfigPath name host
+run (Dump (PkgConfig names) host) = runPkgM Normal $ printPkgConfigPath names host
 run (Dump (IncludePath name) host) = runPkgM Normal $ printIncludePath name host
 run (Dump (LibPath name) host) = runPkgM Normal $ printLibPath name host
 run (Dump (LdLibPath names) host) = runPkgM Normal $ printLdLibPath names host
@@ -166,7 +187,9 @@
     exists <- doesDirectoryExist pkgDir
     when exists $
         removeDirectoryRecursive pkgDir
+run NukeCache = cleanCache
 run (List pkSet) = displayPackageSet pkSet
+run (GarbageCollect v) = runPkgM v garbageCollect
 
 main :: IO ()
 main = run =<< execParser wrapper
diff --git a/cpkg.cabal b/cpkg.cabal
--- a/cpkg.cabal
+++ b/cpkg.cabal
@@ -1,10 +1,10 @@
 cabal-version: 1.18
 name: cpkg
-version: 0.2.2.0
+version: 0.2.3.0
 license: BSD3
 license-file: LICENSE
 copyright: Copyright: (c) 2018-2019 Vanessa McHale
-maintainer: vanessa.mchale@iohk.io
+maintainer: vamchale@gmail.com
 author: Vanessa McHale
 synopsis: Build tool for C
 description:
@@ -58,6 +58,7 @@
         Package.C.Db.Register
         Package.C.Db.Monad
         Package.C.Db.Memory
+        Package.C.Db.GarbageCollect
         Package.C.PackageSet
         Package.C.Logging
         System.Process.Ext
@@ -95,7 +96,8 @@
         network-uri -any,
         megaparsec -any,
         libarchive >=1.0.4.0,
-        dir-traverse >=0.2.1.0
+        dir-traverse >=0.2.1.0,
+        composition-prelude >=1.5.2.0
 
     if (flag(development) && impl(ghc <=8.2))
         ghc-options: -Werror
diff --git a/dhall/cpkg-prelude.dhall b/dhall/cpkg-prelude.dhall
--- a/dhall/cpkg-prelude.dhall
+++ b/dhall/cpkg-prelude.dhall
@@ -555,7 +555,6 @@
       { pkgName = pkg.name
       , pkgVersion = pkg.version
       , pkgSubdir = "${pkg.name}-${showVersion pkg.version}"
-      , pkgBuildDeps = [ unbounded "make" ]
       }
 in
 
@@ -1116,9 +1115,9 @@
 let installPrefix =
   λ(cfg : types.BuildVars) →
       [ call (defaultCall ⫽ { program = "make"
-                             , arguments = [ "prefix=${cfg.installDir}", "PREFIX=${cfg.installDir}", "install" ]
-                             , environment = Some (buildEnv cfg)
-                             })
+                            , arguments = [ "prefix=${cfg.installDir}", "PREFIX=${cfg.installDir}", "install" ]
+                            , environment = Some (buildEnv cfg)
+                            })
       ]
 in
 
diff --git a/pkgs/pkg-set.dhall b/pkgs/pkg-set.dhall
--- a/pkgs/pkg-set.dhall
+++ b/pkgs/pkg-set.dhall
@@ -127,7 +127,6 @@
                 , prelude.copyFile wrapped wrapped
                 , prelude.symlinkBinary wrapped
                 ]
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
       }
 in
 
@@ -258,7 +257,6 @@
       , pkgBuildDeps = [ prelude.unbounded "bison"
                        , prelude.unbounded "gawk"
                        , prelude.unbounded "python3"
-                       , prelude.unbounded "make"
                        ]
       }
 in
@@ -355,7 +353,6 @@
       { pkgUrl = "http://www.nasm.us/pub/nasm/releasebuilds/${prelude.showVersion v}.02/nasm-${prelude.showVersion v}.02.tar.xz"
       , pkgSubdir = "nasm-${prelude.showVersion v}.02"
       , installCommand = prelude.installWithBinaries [ "bin/nasm", "bin/ndisasm" ]
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
       }
 in
 
@@ -373,7 +370,6 @@
 
           prelude.configureWithFlags ([ "--with-shared", "--enable-widec" ] # crossArgs) cfg
           -- enable-widec is necessary because util-linux uses libncursesw
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
       }
 in
 
@@ -386,9 +382,7 @@
 let pcre =
   λ(v : List Natural) →
     prelude.simplePackage { name = "pcre", version = v } ⫽
-      { pkgUrl = "https://ftp.pcre.org/pub/pcre/pcre-${prelude.showVersion v}.tar.bz2"
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
-      }
+      { pkgUrl = "https://ftp.pcre.org/pub/pcre/pcre-${prelude.showVersion v}.tar.bz2" }
 in
 
 let perl5 =
@@ -426,7 +420,6 @@
     prelude.simplePackage { name = "libpng", version = v } ⫽
       { pkgUrl = "https://download.sourceforge.net/libpng/libpng-${prelude.showVersion v}.tar.xz"
       , pkgDeps = [ prelude.unbounded "zlib" ]
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
       }
 in
 
@@ -536,9 +529,7 @@
 let gettext =
   λ(v : List Natural) →
     prelude.makeGnuExe { name = "gettext", version = v } ⫽
-      { installCommand = prelude.installWithBinaries [ "bin/gettext", "bin/msgfmt", "bin/autopoint" ]
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
-      }
+      { installCommand = prelude.installWithBinaries [ "bin/gettext", "bin/msgfmt", "bin/autopoint" ] }
 in
 
 let gzip =
@@ -653,7 +644,11 @@
 let patch =
   λ(v : List Natural) →
     prelude.makeGnuExe { name = "patch", version = v } ⫽
-      { pkgBuildDeps = [] : List types.Dep }
+      { installCommand =
+          λ(cfg : types.BuildVars) →
+            prelude.installWithBinaries [ "bin/patch" ] cfg
+              # prelude.symlinkManpages [ { file = "share/man/man1/patch.1", section = 1 } ]
+      }
 in
 
 let m4 =
@@ -665,9 +660,7 @@
               # prelude.defaultConfigure cfg
       , installCommand =
           prelude.installWithManpages [ { file = "share/man/man1/m4.1", section = 1 } ]
-      , pkgBuildDeps = [ prelude.unbounded "patch"
-                       , prelude.unbounded "make"
-                       ]
+      , pkgBuildDeps = [ prelude.unbounded "patch" ]
       }
 in
 
@@ -721,9 +714,7 @@
 let giflib =
   λ(v : List Natural) →
     prelude.simplePackage { name = "giflib", version = v } ⫽
-      { pkgUrl = "https://downloads.sourceforge.net/giflib/giflib-${prelude.showVersion v}.tar.bz2"
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
-      }
+      { pkgUrl = "https://downloads.sourceforge.net/giflib/giflib-${prelude.showVersion v}.tar.bz2" }
 in
 
 let emacs =
@@ -921,9 +912,7 @@
 let libffi =
   λ(v : List Natural) →
     prelude.simplePackage { name = "libffi", version = v } ⫽
-      { pkgUrl = "https://sourceware.org/ftp/libffi/libffi-${prelude.showVersion v}.tar.gz"
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
-      }
+      { pkgUrl = "https://sourceware.org/ftp/libffi/libffi-${prelude.showVersion v}.tar.gz" }
 in
 
 let gdb =
@@ -947,7 +936,6 @@
     prelude.simplePackage { name = "pkg-config", version = v } ⫽
       { pkgUrl = "https://pkg-config.freedesktop.org/releases/pkg-config-${prelude.showVersion v}.tar.gz"
       , configureCommand = prelude.configureWithFlags [ "--with-internal-glib" ]
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
       }
 in
 
@@ -1095,9 +1083,7 @@
   λ(name : Text) →
   λ(v : List Natural) →
     prelude.simplePackage { name = name, version = v } ⫽
-      { pkgUrl = "https://www.x.org/releases/individual/proto/${name}-${prelude.showVersion v}.tar.bz2"
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
-      }
+      { pkgUrl = "https://www.x.org/releases/individual/proto/${name}-${prelude.showVersion v}.tar.bz2" }
 in
 
 let mkXProtoWithPatch =
@@ -1106,9 +1092,7 @@
   λ(v : List Natural) →
     mkXProto name v ⫽
       { configureCommand = prelude.configureWithPatch patch
-      , pkgBuildDeps = [ prelude.unbounded "patch"
-                       , prelude.unbounded "make"
-                       ]
+      , pkgBuildDeps = [ prelude.unbounded "patch" ]
       }
 in
 
@@ -1757,9 +1741,7 @@
 let xcb-proto =
   λ(v : List Natural) →
     prelude.simplePackage { name = "xcb-proto", version = v } ⫽
-      { pkgUrl = "https://xorg.freedesktop.org/archive/individual/xcb/xcb-proto-${prelude.showVersion v}.tar.bz2"
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
-      }
+      { pkgUrl = "https://xorg.freedesktop.org/archive/individual/xcb/xcb-proto-${prelude.showVersion v}.tar.bz2" }
 in
 
 let libxcb =
@@ -1777,9 +1759,7 @@
 let libpthread-stubs =
   λ(v : List Natural) →
     prelude.simplePackage { name = "libpthread-stubs", version = v } ⫽
-      { pkgUrl = "https://www.x.org/archive/individual/xcb/libpthread-stubs-${prelude.showVersion v}.tar.bz2"
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
-      }
+      { pkgUrl = "https://www.x.org/archive/individual/xcb/libpthread-stubs-${prelude.showVersion v}.tar.bz2" }
 in
 
 let xorgConfigure =
@@ -1815,9 +1795,7 @@
   λ(name : Text) →
   λ(v : List Natural) →
     prelude.simplePackage { name = name, version = v } ⫽
-      { pkgUrl = "https://www.x.org/releases/individual/util/${name}-${prelude.showVersion v}.tar.bz2"
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
-      }
+      { pkgUrl = "https://www.x.org/releases/individual/util/${name}-${prelude.showVersion v}.tar.bz2" }
 in
 
 let libXrender =
@@ -1957,9 +1935,7 @@
 let expat =
   λ(v : List Natural) →
     prelude.simplePackage { name = "expat", version = v } ⫽
-      { pkgUrl = "https://github.com/libexpat/libexpat/releases/download/R_${prelude.underscoreVersion v}/expat-${prelude.showVersion v}.tar.bz2"
-      , pkgBuildDeps = [ prelude.unbounded "make" ]
-      }
+      { pkgUrl = "https://github.com/libexpat/libexpat/releases/download/R_${prelude.underscoreVersion v}/expat-${prelude.showVersion v}.tar.bz2" }
 in
 
 let gperf =
@@ -2179,6 +2155,7 @@
                   , prelude.lowerBound { name = "libepoxy", lower = [1,4] }
                   , prelude.unbounded "libXi"
                   ]
+      , pkgBuildDeps = [ prelude.unbounded "binutils" ]
       }
 in
 
@@ -2285,6 +2262,7 @@
 let libarchive =
   λ(v : List Natural) →
     prelude.simplePackage { name = "libarchive", version = v } ⫽
+    -- https://github.com/libarchive/libarchive/releases/download/v3.4.0/libarchive-3.4.0.tar.gz
       { pkgUrl = "https://www.libarchive.org/downloads/libarchive-${prelude.showVersion v}.tar.gz"
       -- , pkgDeps = [ prelude.unbounded "libxml2" ]
       , pkgDeps = [ prelude.unbounded "xz"
@@ -2424,6 +2402,7 @@
         λ(cfg : types.BuildVars) →
           [ prelude.call (prelude.defaultCall ⫽ { program = prelude.makeExe cfg.buildOS }) ]
       , pkgDeps = [ prelude.unbounded "libXt" ]
+      , pkgBuildDeps = [ prelude.unbounded "binutils" ]
       }
 in
 
@@ -3274,7 +3253,7 @@
   λ(v : List Natural) →
     prelude.simplePackage { name = "pHash", version = v } ⫽
       { pkgUrl = "http://phash.org/releases/pHash-${prelude.showVersion v}.tar.gz"
-      , pkgDeps = [ prelude.unbounded "CImg"
+      , pkgDeps = [ prelude.lowerBound { name = "CImg", lower = [1,3] }
                   , prelude.unbounded "ffmpeg"
                   , prelude.unbounded "libsndfile"
                   , prelude.unbounded "libsamplerate"
@@ -3530,9 +3509,7 @@
     prelude.simplePackage { name = "blas", version = v } ⫽
       { pkgUrl = "http://www.netlib.org/blas/blas-${prelude.showVersion v}.tgz"
       , pkgSubdir = "BLAS-${prelude.showVersion v}"
-      , pkgBuildDeps = [ prelude.unbounded "make"
-                       , prelude.unbounded "gcc"
-                       ]
+      , pkgBuildDeps = [ prelude.unbounded "gcc" ]
       , configureCommand = prelude.doNothing
       , installCommand =
         λ(_ : types.BuildVars) →
@@ -3546,9 +3523,7 @@
     prelude.simplePackage { name = "openblas", version = v } ⫽
       { pkgUrl = "https://github.com/xianyi/OpenBLAS/archive/v${versionString}.tar.gz"
       , pkgSubdir = "OpenBLAS-${versionString}"
-      , pkgBuildDeps = [ prelude.unbounded "make"
-                       , prelude.unbounded "gcc"
-                       ]
+      , pkgBuildDeps = [ prelude.unbounded "gcc" ]
       , pkgDeps = [ prelude.unbounded "gcc" ]
       , configureCommand = prelude.doNothing
       , installCommand = prelude.installPrefix
@@ -3565,13 +3540,12 @@
       , pkgDeps = [ prelude.unbounded "readline"
                   , prelude.unbounded "libXt"
                   ]
-      , pkgBuildDeps = [ prelude.unbounded "make"
-                       , prelude.unbounded "gcc"
-                       ]
+      , pkgBuildDeps = [ prelude.unbounded "gcc" ]
       , installCommand = prelude.installWithBinaries [ "bin/R", "bin/Rscript" ]
       }
 in
 
+-- http://www.linuxfromscratch.org/lfs/view/development/chapter06/findutils.html
 -- TODO: musl-ghc?
 -- https://hub.darcs.net/raichoo/hikari
 -- https://versaweb.dl.sourceforge.net/project/schilytools/schily-2019-03-29.tar.bz2
@@ -3585,7 +3559,7 @@
 , at-spi-core { version = [2,33], patch = 2 }
 , atk { version = [2,33], patch = 3 }
 , babl { version = [0,1], patch = 60 }
-, binutils [2,31]
+, binutils [2,32]
 , bison [3,3,1]
 , blas [3,8,0]
 , bzip2 [1,0,6]
diff --git a/src/CPkgPrelude.hs b/src/CPkgPrelude.hs
--- a/src/CPkgPrelude.hs
+++ b/src/CPkgPrelude.hs
@@ -8,8 +8,10 @@
                    , fold
                    , toList
                    , filterM
+                   , forM_
                    , ($>)
                    , (<=<)
+                   , (<=*<)
                    , MonadIO (..)
                    , Void
                    -- * Dhall reëxports
@@ -30,9 +32,11 @@
                    , (</>)
                    -- * Exports from "System.Directory"
                    , doesFileExist
+                   , removeDirectoryRecursive
                    , getAppUserDataDirectory
                    ) where
 
+import           Control.Composition       ((<=*<))
 import           Control.Monad
 import           Control.Monad.IO.Class    (MonadIO (..))
 import           Data.Binary               (Binary)
diff --git a/src/Package/C.hs b/src/Package/C.hs
--- a/src/Package/C.hs
+++ b/src/Package/C.hs
@@ -29,6 +29,9 @@
                  , printLdLibPath
                  , printCabalFlags
                  , buildByName
+                 , uninstallPkgByName
+                 , garbageCollect
+                 , cleanCache
                  -- * Dhall functionality
                  , cPkgDhallToCPkg
                  , getCPkg
@@ -44,6 +47,7 @@
 
 import           Package.C.Build
 import           Package.C.Build.Tree
+import           Package.C.Db.GarbageCollect
 import           Package.C.Db.Monad
 import           Package.C.Db.Register
 import           Package.C.Db.Type
diff --git a/src/Package/C/Build.hs b/src/Package/C/Build.hs
--- a/src/Package/C/Build.hs
+++ b/src/Package/C/Build.hs
@@ -117,12 +117,13 @@
           -> Maybe TargetTriple
           -> Bool -- ^ Should we build static libraries?
           -> Bool -- ^ Should we install globally?
+          -> Bool -- ^ Was this package installed manually?
           -> [FilePath] -- ^ Shared data directories
           -> [FilePath] -- ^ Library directories
           -> [FilePath] -- ^ Include directories
           -> [FilePath] -- ^ Directories to add to @PATH@
           -> PkgM ()
-buildCPkg cpkg host sta glob shr libs incls bins = do
+buildCPkg cpkg host sta glob usr shr libs incls bins = do
 
     buildVars <- getVars host sta shr libs incls bins
 
@@ -133,7 +134,7 @@
         putDiagnostic ("Package " ++ pkgName cpkg ++ " already installed, skipping.")
 
     unless installed $
-        forceBuildCPkg cpkg host glob buildVars
+        forceBuildCPkg cpkg host glob usr buildVars
 
 getPreloads :: [ FilePath ] -> IO [ FilePath ]
 getPreloads =
@@ -170,9 +171,10 @@
 forceBuildCPkg :: CPkg
                -> Maybe TargetTriple
                -> Bool
+               -> Bool -- ^ Manually installed?
                -> BuildVars
                -> PkgM ()
-forceBuildCPkg cpkg host glob buildVars = do
+forceBuildCPkg cpkg host glob usr buildVars = do
 
     pkgDir <- cPkgToDir cpkg host glob buildVars
 
@@ -202,4 +204,4 @@
 
         installInDir cpkg buildConfigured p' pkgDir
 
-        registerPkg cpkg host glob buildVars -- not configured
+        registerPkg cpkg host glob usr buildVars -- not configured
diff --git a/src/Package/C/Build/Tree.hs b/src/Package/C/Build/Tree.hs
--- a/src/Package/C/Build/Tree.hs
+++ b/src/Package/C/Build/Tree.hs
@@ -21,7 +21,7 @@
 
 getAll :: [BuildDirs] -> BuildDirs
 getAll bds =
-    let go f = fold (f <$> bds)
+    let go f = concat (f <$> bds)
     in BuildDirs (go libraries) (go share) (go include) (go binaries)
 
 -- in order to prevent the "vanilla" libffi from preceding the *cross* libffi,
@@ -51,12 +51,13 @@
 buildWithContext cTree host sta glob = zygoM' dirAlg buildAlg cTree
 
     where buildAlg :: DepTreeF CPkg (BuildDirs, ()) -> PkgM ()
-          buildAlg (DepNodeF c preBds) =
-            buildCPkg c host sta glob ds (immoralFilter host ls) is (filterCross host bs)
+          buildAlg (DepNodeF c usr preBds) =
+            buildCPkg c host sta glob usr ds (immoralFilter host ls) is (filterCross host bs)
                 where (BuildDirs ls ds is bs) = getAll (fst <$> preBds)
           buildAlg (BldDepNodeF c preBds) =
-            buildCPkg c Nothing False False ds ls is bs -- don't use static libraries for build dependencies
-            -- also don't install them globally for obvious reasons
+            buildCPkg c Nothing False False False ds ls is bs -- don't use static libraries for build dependencies
+            -- also don't install them globally
+            -- build dependencies are not manual!
                 where (BuildDirs ls ds is bs) = getAll (fst <$> preBds)
 
           mkBuildDirs :: MonadIO m => FilePath -> BuildDirs -> m BuildDirs
@@ -79,7 +80,7 @@
             pure (BuildDirs (nubOrd links) (nubOrd shares) (nubOrd includes) (nubOrd bins))
 
           dirAlg :: DepTreeF CPkg BuildDirs -> PkgM BuildDirs
-          dirAlg (DepNodeF c bds) = do
+          dirAlg (DepNodeF c _ bds) = do
 
             let bldDirs@(BuildDirs ls ds is bs) = getAll bds
 
@@ -100,6 +101,7 @@
             mkBuildDirs pkgDir bldDirs
 
 -- TODO: should this parse a string into a TargetTriple instead?
+-- | Manually install a package
 buildByName :: PackId -> Maybe TargetTriple -> Maybe String -> Bool -> Bool -> PkgM ()
 buildByName pkId host pkSet sta glob = do
     allPkgs <- liftIO (pkgsM pkId pkSet)
diff --git a/src/Package/C/Db/GarbageCollect.hs b/src/Package/C/Db/GarbageCollect.hs
new file mode 100644
--- /dev/null
+++ b/src/Package/C/Db/GarbageCollect.hs
@@ -0,0 +1,84 @@
+{-# LANGUAGE FlexibleContexts #-}
+
+module Package.C.Db.GarbageCollect ( cleanSymlinks
+                                   , cleanCache
+                                   , garbageCollect
+                                   ) where
+
+import           Control.Monad.Reader  (MonadReader)
+import           CPkgPrelude
+import qualified Data.Set              as S
+import qualified Data.Text             as T
+import           Package.C.Db.Memory   (globalPkgDir)
+import           Package.C.Db.Monad    (MonadDb)
+import           Package.C.Db.Register
+import           Package.C.Db.Type
+import           Package.C.Logging     (putDiagnostic)
+import           Package.C.Type        (TargetTriple, Verbosity)
+import           System.Directory      (doesDirectoryExist, doesFileExist, getSymbolicLinkTarget, listDirectory, removeDirectoryRecursive, removeFile)
+import           System.FilePath       ((</>))
+
+getTransitiveDepsByName :: (MonadIO m, MonadDb m) => String -> Maybe TargetTriple -> m (S.Set BuildCfg)
+getTransitiveDepsByName = getTransitiveDeps <=*< lookupOrFail
+
+garbageCollect :: (MonadIO m, MonadDb m, MonadReader Verbosity m)
+               => m ()
+garbageCollect = garbageCollectPkgs *> cleanSymlinks
+
+-- TODO: garbage collect old packages as well, and things which are broken b/c
+-- their dependencies are gone
+--
+-- | @since 0.2.3.0
+garbageCollectPkgs :: (MonadIO m, MonadDb m, MonadReader Verbosity m)
+                   => m ()
+garbageCollectPkgs = do
+    allPkgs <- installedDb
+    let manuals = (toList . S.filter manual) allPkgs
+    putDiagnostic ("Manually installed packages: " ++ show (buildName <$> manuals))
+    allDeps <- S.unions <$> traverse getTransitiveDeps manuals
+    let redundant = allPkgs S.\\ allDeps
+    putDiagnostic ("Redundant packages: " ++ show (buildName <$> toList redundant))
+    traverse_ uninstallPkg redundant
+
+getTransitiveDeps :: (MonadIO m, MonadDb m) => BuildCfg -> m (S.Set BuildCfg)
+getTransitiveDeps cfg = do
+    let names = fst <$> pinnedDeps cfg
+        host = targetArch cfg
+    next <- traverse (\n -> getTransitiveDepsByName n host) (T.unpack <$> names)
+    pure $ S.insert cfg (S.unions next)
+
+-- | @since 0.2.3.0
+cleanCache :: MonadIO m => m ()
+cleanCache = liftIO $ do
+    ccDir <- (</> "cache") <$> globalPkgDir
+    exists <- doesDirectoryExist ccDir
+    when exists $
+        removeDirectoryRecursive ccDir
+
+cleanSymlinks :: (MonadReader Verbosity m, MonadIO m) => m ()
+cleanSymlinks = do
+    pkDir <- liftIO globalPkgDir
+    let binDir = pkDir </> "bin"
+        manDir = pkDir </> "share" </> "man"
+        man1Dir = manDir </> "man1"
+        man3Dir = manDir </> "man3"
+    traverse_ cleanDir
+        [binDir, man1Dir, man3Dir]
+
+
+cleanDir :: (MonadReader Verbosity m, MonadIO m) => FilePath -> m ()
+cleanDir dir = do
+    exists <- liftIO $ doesDirectoryExist dir
+    when exists $ do
+        links <- liftIO $ listDirectory dir
+        forM_ links $ \link -> do
+            let linkAbs = dir </> link
+            brk <- liftIO $ isBroken linkAbs
+            when brk $
+                putDiagnostic ("Removing link " ++ linkAbs ++ "...") *>
+                liftIO (removeFile linkAbs)
+
+isBroken :: FilePath -> IO Bool
+isBroken = (fmap not . doesFileExist) <=< getSymbolicLinkTarget
+
+-- getSymbolicLinkTarget
diff --git a/src/Package/C/Db/Register.hs b/src/Package/C/Db/Register.hs
--- a/src/Package/C/Db/Register.hs
+++ b/src/Package/C/Db/Register.hs
@@ -4,6 +4,11 @@
 -- TODO: a lot of the stuff in this module could be made pure so that it only
 -- gets called once
 module Package.C.Db.Register ( registerPkg
+                             , unregisterPkg
+                             , uninstallPkg
+                             , uninstallPkgByName
+                             , installedDb
+                             , lookupOrFail
                              , cPkgToDir
                              , globalPkgDir
                              , printCompilerFlags
@@ -50,8 +55,8 @@
 printLinkerFlags :: (MonadIO m, MonadDb m) => String -> Maybe Platform -> m ()
 printLinkerFlags = printFlagsWith buildCfgToLinkerFlags
 
-printPkgConfigPath :: (MonadIO m, MonadDb m) => String -> Maybe Platform -> m ()
-printPkgConfigPath = printFlagsWith buildCfgToPkgConfigPath
+printPkgConfigPath :: (MonadIO m, MonadDb m) => [String] -> Maybe Platform -> m ()
+printPkgConfigPath = printMany (liftIO . putStrLn <=< (fmap (intercalate ":") . traverse buildCfgToPkgConfigPath))
 
 printIncludePath :: (MonadIO m, MonadDb m) => String -> Maybe Platform -> m ()
 printIncludePath = printFlagsWith buildCfgToIncludePath
@@ -111,6 +116,11 @@
 buildCfgToIncludePath :: MonadIO m => BuildCfg -> m String
 buildCfgToIncludePath = fmap (</> "include") . buildCfgToDir
 
+installedDb :: (MonadIO m, MonadDb m)
+                  => m (S.Set BuildCfg)
+installedDb =
+    _installedPackages <$> memIndex
+
 packageInstalled :: (MonadIO m, MonadDb m)
                  => CPkg
                  -> Maybe TargetTriple
@@ -119,34 +129,77 @@
                  -> m Bool
 packageInstalled pkg host glob b = do
 
-    indexContents <- memIndex
+    packs <- installedDb
 
-    pure (pkgToBuildCfg pkg host glob b `S.member` _installedPackages indexContents)
+    pure $
+           (pkgToBuildCfg pkg host glob True b `S.member` packs)
+        || (pkgToBuildCfg pkg host glob False b `S.member` packs)
 
 lookupPackage :: (MonadIO m, MonadDb m) => String -> Maybe TargetTriple -> m (Maybe BuildCfg)
 lookupPackage name host = do
 
-    indexContents <- memIndex
+    packs <- installedDb
 
-    let matches = S.filter (\pkg -> buildName pkg == name && targetArch pkg == host) (_installedPackages indexContents)
+    let matches = S.filter (\pkg -> buildName pkg == name && targetArch pkg == host) packs
 
     pure (S.lookupMax matches)
 
+lookupOrFail :: (MonadIO m, MonadDb m) => String -> Maybe TargetTriple -> m BuildCfg
+lookupOrFail name host = do
+    pk <- lookupPackage name host
+    case pk of
+        Just cfg -> pure cfg
+        Nothing  -> notInstalled name
+
+-- | @since 0.2.3.0
+uninstallPkgByName :: (MonadReader Verbosity m, MonadIO m, MonadDb m)
+                   => String
+                   -> Maybe TargetTriple
+                   -> m ()
+uninstallPkgByName name host =
+    uninstallPkg =<< lookupOrFail name host
+
+uninstallPkg :: (MonadIO m, MonadDb m, MonadReader Verbosity m)
+             => BuildCfg
+             -> m ()
+uninstallPkg cpkg = do
+    unregisterPkg cpkg
+    (liftIO . removeDirectoryRecursive)
+        =<< buildCfgToDir cpkg
+
+unregisterPkg :: (MonadIO m, MonadDb m, MonadReader Verbosity m)
+              => BuildCfg
+              -> m ()
+unregisterPkg buildCfg = do
+
+    putLoud ("Unregistering package " ++ buildName buildCfg ++ "...")
+
+    indexFile <- pkgIndex
+    indexContents <- memIndex
+
+    let modIndex = over installedPackages (S.delete buildCfg)
+        newIndex = modIndex indexContents
+
+    modify modIndex
+
+    liftIO $ BSL.writeFile indexFile (encode newIndex)
+
 -- TODO: replace this with a proper/sensible database
 registerPkg :: (MonadIO m, MonadDb m, MonadReader Verbosity m)
             => CPkg
             -> Maybe TargetTriple
-            -> Bool
+            -> Bool -- ^ Globally installed?
+            -> Bool -- ^ Manually installed?
             -> BuildVars
             -> m ()
-registerPkg cpkg host glob b = do
+registerPkg cpkg host glob usr b = do
 
     putDiagnostic ("Registering package " ++ pkgName cpkg ++ "...")
 
     indexFile <- pkgIndex
     indexContents <- memIndex
 
-    let buildCfg = pkgToBuildCfg cpkg host glob b
+    let buildCfg = pkgToBuildCfg cpkg host glob usr b
         modIndex = over installedPackages (S.insert buildCfg)
         newIndex = modIndex indexContents
 
@@ -157,10 +210,13 @@
 pkgToBuildCfg :: CPkg
               -> Maybe TargetTriple
               -> Bool
+              -> Bool -- ^ Was this package manually installed?
               -> BuildVars
               -> BuildCfg
-pkgToBuildCfg (CPkg n v _ _ _ _ _ cCmd bCmd iCmd) host glob bVar =
-    BuildCfg n v mempty mempty host glob (cCmd bVar) (bCmd bVar) (iCmd bVar) -- TODO: fix pinned build deps &c.
+pkgToBuildCfg (CPkg n v _ _ _ bds ds cCmd bCmd iCmd) host glob usr bVar =
+    BuildCfg n v (go <$> bds) (go <$> ds) host glob (cCmd bVar) (bCmd bVar) (iCmd bVar) usr -- TODO: fix pinned build deps &c.
+    where placeholderVersion = Version [0,1,0,0]
+          go (Dep n' _) = (n', placeholderVersion)
 
 platformString :: Maybe TargetTriple -> (FilePath -> FilePath -> FilePath)
 platformString Nothing  = (</>)
@@ -169,7 +225,9 @@
 buildCfgToDir :: MonadIO m => BuildCfg -> m FilePath
 buildCfgToDir buildCfg = do
     global' <- globalPkgDir
-    let hashed = showHex (abs (hash buildCfg)) mempty
+    -- when hashing, pretend everything has was NOT manually installed so they
+    -- all have the same hash
+    let hashed = showHex (abs (hash (buildCfg { manual = False}))) mempty
         (<?>) = platformString (targetArch buildCfg)
     pure (global' <?> buildName buildCfg ++ "-" ++ showVersion (buildVersion buildCfg) ++ "-" ++ hashed)
 
@@ -183,5 +241,5 @@
           -> Bool
           -> BuildVars
           -> m FilePath
-cPkgToDir pk host False bv = buildCfgToDir (pkgToBuildCfg pk host False bv)
+cPkgToDir pk host False bv = buildCfgToDir (pkgToBuildCfg pk host False undefined bv)
 cPkgToDir _ host _ _       = pure (globDir host)
diff --git a/src/Package/C/Db/Type.hs b/src/Package/C/Db/Type.hs
--- a/src/Package/C/Db/Type.hs
+++ b/src/Package/C/Db/Type.hs
@@ -32,4 +32,6 @@
                          , configureCmds   :: [ Command ]
                          , buildCmds       :: [ Command ]
                          , installCmds     :: [ Command ]
+                         -- , tarball         :: FilePath
+                         , manual          :: Bool -- ^ Was this package manually installed?
                          } deriving (Eq, Ord, Generic, Binary, Hashable)
diff --git a/src/Package/C/Error.hs b/src/Package/C/Error.hs
--- a/src/Package/C/Error.hs
+++ b/src/Package/C/Error.hs
@@ -6,6 +6,7 @@
                        , corruptedDatabase
                        , unfoundPackage
                        , parseErr
+                       , notInstalled
                        , PackageError (..)
                        ) where
 
@@ -19,18 +20,23 @@
                   | IndexError String -- package name
                   | CorruptedDatabase
                   | UnfoundPackage -- TODO: this should take the package name as an argument
+                  | NotInstalled String
                   | ParseFailed String
                   -- TODO: libarchive error
 
 instance Pretty PackageError where
-    pretty (Unrecognized t)  = "Error: Unrecognized archive format when unpacking" <#> hang 2 (pretty t) <> hardline
-    pretty (IndexError str)  = "Error: Package" <+> pretty str <+> "not found in your indices. Try 'cpkg install" <+> pretty str <> "'." <> hardline
-    pretty CorruptedDatabase = "Error: Package database corrupted. Please try 'cpkg nuke'" <> hardline
-    pretty UnfoundPackage    = "Error: Package not found" <> hardline
-    pretty (ParseFailed str) = "Parse error:" <+> pretty str
+    pretty (Unrecognized t)   = "Error: Unrecognized archive format when unpacking" <#> hang 2 (pretty t) <> hardline
+    pretty (IndexError str)   = "Error: Package" <+> pretty str <+> "not found in your indices. Try 'cpkg install" <+> pretty str <> "'." <> hardline
+    pretty CorruptedDatabase  = "Error: Package database corrupted. Please try 'cpkg nuke'" <> hardline
+    pretty UnfoundPackage     = "Error: Package not found" <> hardline
+    pretty (ParseFailed str)  = "Parse error:" <+> pretty str
+    pretty (NotInstalled pkg) = "Package" <+> pretty pkg <+> "is not installed, so not removed." <> hardline
 
 printErr :: MonadIO m => PackageError -> m a
 printErr e = liftIO (putDoc (pretty e) *> exitFailure)
+
+notInstalled :: MonadIO m => String -> m a
+notInstalled = printErr . NotInstalled
 
 unrecognized :: MonadIO m => String -> m a
 unrecognized = printErr . Unrecognized
diff --git a/src/Package/C/PackageSet.hs b/src/Package/C/PackageSet.hs
--- a/src/Package/C/PackageSet.hs
+++ b/src/Package/C/PackageSet.hs
@@ -45,20 +45,20 @@
 
         in PackageSet $ M.fromList (zip names pkgs')
 
-getDeps :: PackId -> PackageSet -> Maybe (DepTree PackId)
-getDeps pkgName' set@(PackageSet ps) = do
+getDeps :: PackId -> Bool -> PackageSet -> Maybe (DepTree PackId)
+getDeps pkgName' usr set@(PackageSet ps) = do
     cpkg <- M.lookup pkgName' ps
     let depNames = name <$> pkgDeps cpkg
         bldDepNames = name <$> pkgBuildDeps cpkg
         ds = nubOrd depNames
         bds = nubOrd bldDepNames
-    nextDeps <- traverse (\p -> getDeps p set) ds
-    nextBldDeps <- traverse (\p -> asBldDep <$> getDeps p set) bds
-    pure $ DepNode pkgName' (nextDeps ++ nextBldDeps)
+    nextDeps <- traverse (\p -> getDeps p False set) ds
+    nextBldDeps <- traverse (\p -> asBldDep <$> getDeps p False set) bds
+    pure $ DepNode pkgName' usr (nextDeps ++ nextBldDeps)
 
 -- TODO: use dfsForest but check for cycles
 pkgPlan :: PackId -> PackageSet -> Maybe (DepTree PackId)
-pkgPlan = getDeps
+pkgPlan pkId = getDeps pkId True -- manually installed
 
 pkgs :: PackId -> PackageSet -> Maybe (DepTree CPkg)
 pkgs pkId set@(PackageSet pset) = do
diff --git a/src/Package/C/Type/Tree.hs b/src/Package/C/Type/Tree.hs
--- a/src/Package/C/Type/Tree.hs
+++ b/src/Package/C/Type/Tree.hs
@@ -12,16 +12,16 @@
 import           Control.Recursion
 import           GHC.Generics      (Generic)
 
-data DepTree p = DepNode p [DepTree p]
+data DepTree p = DepNode p Bool [DepTree p]
                | BldDepNode p [DepTree p]
     deriving (Functor, Foldable, Traversable, Generic, Recursive)
 
-data DepTreeF p x = DepNodeF { self :: p, deps :: [x] }
+data DepTreeF p x = DepNodeF { self :: p, man :: Bool, deps :: [x] }
                   | BldDepNodeF { self :: p, deps :: [x] }
                   deriving (Functor, Foldable, Traversable, Generic)
 
 type instance Base (DepTree a) = DepTreeF a
 
 asBldDep :: DepTree p -> DepTree p
-asBldDep (DepNode p ps)    = BldDepNode p (fmap asBldDep ps)
+asBldDep (DepNode p _ ps)  = BldDepNode p (fmap asBldDep ps)
 asBldDep (BldDepNode p ps) = BldDepNode p (fmap asBldDep ps)